Add error logical.ErrUpstreamRateLimited and return 502 from RespondC…

…ommonError

logical/error.go

@@ -20,6 +20,10 @@ var (
 	// ErrMultiAuthzPending is returned if the the request needs more
 	// authorizations
 	ErrMultiAuthzPending = errors.New("request needs further approval")
+
+	// ErrUpstreamRateLimited is returned when Vault recieves a rate limited
+	// response from an upstream
+	ErrUpstreamRateLimited = errors.New("upstream rate limited")
 )
 
 type HTTPCodedError interface {

logical/response_util.go

@@ -105,6 +105,8 @@ func RespondErrorCommon(req *Request, resp *Response, err error) (int, error) {
 			statusCode = http.StatusNotFound
 		case errwrap.Contains(err, ErrInvalidRequest.Error()):
 			statusCode = http.StatusBadRequest
+		case errwrap.Contains(err, ErrUpstreamRateLimited.Error()):
+			statusCode = http.StatusBadGateway
 		}
 	}
 

logical/response_util_test.go

@@ -0,0 +1,83 @@
+package logical
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestResponseUtil_RespondErrorCommon_basic(t *testing.T) {
+	testCases := []struct {
+		title          string
+		req            *Request
+		resp           *Response
+		respErr        error
+		expectedStatus int
+		expectedErr    error
+	}{
+		{
+			title:          "Throttled, no error",
+			respErr:        ErrUpstreamRateLimited,
+			resp:           &Response{},
+			expectedStatus: 502,
+		},
+		{
+			title:   "Throttled, with error",
+			respErr: ErrUpstreamRateLimited,
+			resp: &Response{
+				Data: map[string]interface{}{
+					"error": "rate limited",
+				},
+			},
+			expectedStatus: 502,
+		},
+		{
+			title: "Read not found",
+			req: &Request{
+				Operation: ReadOperation,
+			},
+			respErr:        nil,
+			expectedStatus: 404,
+		},
+		{
+			title: "List with response and no keys",
+			req: &Request{
+				Operation: ListOperation,
+			},
+			resp:           &Response{},
+			respErr:        nil,
+			expectedStatus: 404,
+		},
+		{
+			title: "List with response and keys",
+			req: &Request{
+				Operation: ListOperation,
+			},
+			resp: &Response{
+				Data: map[string]interface{}{
+					"keys": []string{"some", "things", "here"},
+				},
+			},
+			respErr:        nil,
+			expectedStatus: 0,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.title, func(t *testing.T) {
+			var status int
+			var err, respErr error
+			if tc.respErr != nil {
+				respErr = tc.respErr
+			}
+			status, err = RespondErrorCommon(tc.req, tc.resp, respErr)
+			if status != tc.expectedStatus {
+				t.Fatalf("Expected (%d) status code, got (%d)", tc.expectedStatus, status)
+			}
+			if tc.expectedErr != nil {
+				if !strings.Contains(tc.expectedErr.Error(), err.Error()) {
+					t.Fatalf("Expected error to contain:\n%s\n\ngot:\n%s\n", tc.expectedErr, err)
+				}
+			}
+		})
+	}
+}